Utility knives and box cutters often employ a mechanism for extending a blade from a housing and a release mechanism for retracting the blade into the housing. The housing usually comprises a hollow portion that accommodates a slidable blade carrier that secures a razor blade. The mechanism for extending the blade is commonly a sliding actuator positioned outside the housing and, thus, engageable with a user's thumb, wherein movement of the actuator either extends the blade from the housing or retracts the blade into the housing. Some utility knives are indexed, i.e., the blade may be moved between one of several locked positions, including fully retracted and fully extended. A common utility knife is shown in U.S. Pat. No. 4,621,425.
Another type of utility knife provides the ability to automatically retract the blade, wherein the blade is normally retracted in the housing and requires the user to apply pressure on the actuator to maintain the blade in a fully or partially deployed state. A spring interconnecting the housing and the blade carrier automatically retracts the blade upon actuator release. Spring tension may be such that when the blade is extended and inserted into the material being cut, e.g., cardboard, frictional influences between the blade and the material will maintain the blade in the extended position. Automatically retractable utility knives are described, for example, in U.S. Pat. Nos. 4,139,939 and 5,012,581.
It is a long-felt need to provide a utility knife with an automatically-retractable blade that can be selectively locked in an extended, deployed configuration. This disclosure describes a utility knife that employs a selectively-extendable and automatically-retractable blade that also includes additional tools and features.